Why do requirements change?1. They missed a requirement. A stakeholder might realize some missing a feature.
2. A change can be needed because of a detected defect.
3. Some mismatch in stakeholder's expectations from what they see in prototypes or working system (when they see it).
4. The political issues within the organization and between various stakeholders.
5. The marketplace changes.
6. Law changes. This might change some legal aspects of the system based on what was being made. For example, if a taxation system is needed, Tax policies might change and system might needs to be changed as per the latest laws.